There is known a multilayer bottle having at least an outer layer and an inner layer which are adhered entirely throughout an overall circumference to be integrated into one so that the outer layer and the inner layer are not separated from each other.
When a long time has passed after the bottle is filled with a content, for example, oxygen and the like in the content may be volatilized to thereby reduce the pressure in the bottle, even if the bottle is tightly sealed.
There is also known a bottle of the type having a pump attached to a mouth of the bottle, in which the pump is operated to discharge a liquid content contained in the bottle. In this bottle also, the pressure in the bottle is reduced as the liquid content is discharged by the pump.
In such an event, a conventional multilayer bottle is disadvantageous in that an outer layer 2, namely, a bottle body is crushed together with an inner layer 1 to change the external configuration of the bottle, as illustrated in FIG. 12. This results in deterioration of a commercial value.
The change in said configuration is indefinite. In so distorted bottle, the content is liable to remain in an irregular portion formed in the inner layer as a result of the distortion, even if the mouth is positioned downwards. Thus, it is difficult to take out the content quantitatively and efficiently.
It is a technical thema of this invention to prevent any change in the external configuration of a bottle due to a reduction of the pressure in the bottle.